Venera 10 Lander image of the surface of Venus at about 16 N, 291 E. The Lander touched down at 5:17 UT on 25 October 1975 and returned this image during the 65 minutes of operation on the surface. The sun was near zenith during this time, the lighting was about what would be seen on Earth on an overcast summer day. The objects at the bottom of the image are parts of the spacecraft. The image shows flat slabs of rock, partly covered by fine-grained material, not unlike a volcanic area on Earth. The large slab in the foreground extends over 2 meters across. Automatic gain control and logarithmic quantization were used to handle the unknown dynamic range of illumination. The raw image was converted to optical density according to Russian calibration data, then to linear radiance for image processing. It was interpolated with windowed sinc filter to avoid post-aliasing (a "pixilated" appearance), and the modulation transfer function ("aperture") of the camera was corrected with a 1 + 0.2*frequency**2 emphasis. This was then written out as 8-bit gamma-corrected values, using the sRGB standard gamma of 2.2. The bottom image is a digitally in-painted version, using Bertalmio's isophote-flow algorithm. (Venera 10 Lander, processed surface image) (Image posted with permission, copyright 2003 Don P. Mitchell. All rights reserved.) *Image Credit*: NASA
